The general aim of this work is to develop new concepts and techniques which will lead to an understanding of the basic problem in photobiology: how the energy of light is efficiently converted into chemical or electrical energy across the basic biological structure, the membrane. The lipid bilayer is a good model of biological membranes and we have observed photo-initiated charge-transfer across these bilayer interfaces. The kinetics of these photoreactions are powerful probes of the previously inaccessable region of a few angstroms at this interface. The smallness of this region belies its importance throughout biology, from cell recognition to nerve impulses. We will attempt to understand this critical region by studying the effect of various parameters such as ionic charge, ionic strength, structure of pigment and lipid on the kinetics of these laser stimulated reactions. The kinetics will be followed both by electrical (photo-emf and photoconductance) and by optical (double pulse, fluorescence) means. This research will also open up the sub-microsecond time range to membrane studies. These techniques are directly transferable to studies of biological membranes. BIBLIOGRAPHIC REFERENCES: Hong, F.T. and Mauzerall, D., "Photoreactions at the Lipid Bilayer-water Interface". Symposium V. Photoelectric Bilayer Lipid Membranes. 3rd Annual Meeting of American Society for Photochemistry and Photobiology Abstr. WPM-B-4. (1975). Hong, F. T. and Mauzerall, D., Tunable Voltage Clamp Method-Application to Photoelectrical Effects in Pigmented Bilayer Lipid Membranes". J. Electrochem. Soc. in press (1976).